Turbulence: All Mixed Up

Turbulence is disordered motion of a fluid.
What does disordered mean? Well, as some scientists are fond of saying,
"it's hard to define but you'll know it when you see it" (the same can be said
for alot of other things too, including life
itself).

You can get a good idea of what turbulence is by thinking about what all turbulent flows have in common:

Vorticity
A spinning column of fluid is called a vortex (plural vortices)
and since turbulence is loaded with vortices we say it possesses vorticity.
This is especially true if the object itself is spinning like a planet or
star in which case vorticity is generated by the
Coriolis effect. Examples of vortices include tornadoes and hurricanes
on Earth, dust devils on Mars, and the Great Red Spot on Jupiter. Even
spiral galaxies are vorticies.

A wide range of
scalesScales here means different sizes and time intervals.
For example, Jupiter's atmosphere has vortices more than 100,000
km (60,000 miles) wide which encircle the entire planet,
vortices less that 1 km (0.6 miles) wide which are no
bigger than a tornado, and everything in between, including
the Great
Red Spot, which is about 15,000 km (10,000 miles) across.

Unpredictability (chaos)
Turbulence is unpredictable in the sense that two turbulent flows which look
almost exactly the same at one instant may look completely different a short
time later. This is sometimes called the
butterfly effect and it's the reason why we have to use statistics to
describe turbulence. For example, scientists can predict the probable path
of a hurricane but they can never be 100% certain.

Efficient mixing and dissipation
Turbulent fluids are good at stirring; if you
put milk in your tea turbulence will mix it up
far more rapidly than if you put milk in a cup of molasses.
Turbulence also is good at dissipating energy - this is
why cars and airplanes are designed to be as streamlined
as possible. Streamlined shapes reduce turbulence and
therefore reduce drag.

In astronomical objects such as planets and stars turbulence
is usually caused by buoyancy (warm fluid rises and cool fluid
sinks due to gravity) or shear (winds or currents going in
different directions).

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